1. Field of the Invention
The present invention is directed to a catheter, particularly an intra-vascular catheter, having at least one magnetic field-generating element arranged in the catheter envelope in the region of the catheter tip.
2. Description of the Prior Art
A catheter is an elongated instrument that, for example, is inserted into a vessel track of the human or animal body up to a certain point. For example, such catheters are utilized in the framework of treating diseases of the arterial coronary vessels that cause a cardiac infarction. In the case of arteriosclerosis, deposits (arteriosclerotic plaque) occur at the vessel wall and thus lead to a “plugging” of one or more coronary vessels. By employment of a catheter, the diseased vessel regions can be reached and treatment activity can be undertaken.
For moving and guiding the catheter inserted into the vessel, it is known to employ an externally generated magnetic field with which the magnetic field of a permanent magnet arranged in the region of the catheter tip interacts. For example, U.S. Pat. No. 6,148,823 discloses such a system. It is necessary to vary the external magnetic field for moving the catheter. This ensues in the known system using a C-like device to generate the external magnetic field that is arranged so as to be movable at the floor side. The open ends of the C-like device are arranged above and below the patient, so that the device can be displaced relative to the patient. A disadvantage, however, is that this field-generating device is very heavy and is thus somewhat difficult to move. Difficulties arise due the cumbersome nature of the device particularly when the catheter is to be moved around a vessel bend, where it encounters greater resistance and is prone to become lodged. A further disadvantage is that, due to the employment of a permanent magnet in the catheter, the magnetic coupling between its magnetic field and the external magnetic field may not be strong enough in order to overcome the aforementioned resistance, for example because the external magnetic field is somewhat attenuated in the region where the magnetic tip of the catheter is located.
German OS 40 37 586 discloses a medical probe for examining a body that emits electromagnetic waves that are acquired by a receiver arranged outside the body, allowing the probe can be localized. For example, this can then be presented in an X-ray image.
U.S. Pat. No. 6,298,261 discloses a catheter tracking system. A number of transducers are utilized as locating aids, one of which is arranged on the head of the catheter.
German OS 42 15 901 discloses a catheter having a localizable end region for locating the catheter or the catheter tip.
German OS 198 35 658 discloses a method for localizing an MR endoscope wherein rapidly changing magnetic fields at 10-200 Hz or 1 through 120 MHz are utilized in order to determine the position of a probe. This particularly serves the purpose of avoiding direct current and the forces generated therewith.
U.S. Pat. No. 6,317,091 discloses an apparatus for inductively coupling a magnetic resonance signal into a reception antenna as well as a medical intervention instrument.
U.S. Pat. No. 6,280,385 discloses an MR imaging method for the presentation, position identification or functional control of a device introduced into an examination subject, as well as an apparatus for employment in such a method that has various coil arrangements for locating or displaying the catheter tip.
German OS 196 29 890 discloses magnetic resonance devices suitable for re-adjustment as well as imaging for the locating and position determination of a catheter and, additionally, for MR imaging.
British Specification 2 313 668 discloses a sampling ultrasound probe with locally driven wobble ultrasound source for generating ultrasound images.
These systems only serve the purpose of locating a catheter. The aforementioned problems in the manual movement of the catheter by a physician thus continue to exist. The physician is also not provided with any further information by these locating systems.